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— DESCRIPTIVE BULLETIN

UFESTM

Ultra-fast earthing switch

—ABB Inc.Medium Voltage Service2300 Mechanicsville RoadFlorence, South Carolina 29501Phone: +1 800 HELP 365 (option 7) +1 843 665 4144

www.abb.com/mediumvoltagewww.abb.us/mvservice

The information contained in this document is for general information purposes only. While ABB strives to keep the information up to date and correct, it makes no repre-sentations or warranties of any kind, express or implied, about the completeness, accuracy, reliability, suitability or availability with respect to the information, products, ser-vices, or related graphics contained in the document for any purpose. Any reliance placed on such information is therefore strictly at your own risk. ABB reserves the right to discontinue any product or service at any time.

© Copyright 2017 ABB. All rights reserved.

D E SCR IP TI V E B U L L E TIN 32 U F E S T M U LTR A - FA S T E A RTH I N G S W ITCH

—The UFES (ultra-fast earthing switch) is a combination of devices consisting of an electronic device and the corresponding primary switching elements which initiate a three-phase grounded bolted fault in the event of a fault. The extremely short switching time of the primary switching element ensures that an arc fault is extinguished almost immediately after it arises.

— Table of contents

004 UFESTM arc fault protection for switchgear

005 Ultra-fast earthing switch

006 Application example

007 Active protection for switchgear

4 D E SCR IP TI V E B U L L E TINU F E S T M U LTR A - FA S T E A RTH I N G S W ITCH 5

An active arc fault protection system based on the know-how gained from decades of experi-ence with the ABB vacuum interrupter and IS-limiter technology now effectively helps to avoid these negative effects if a fault should oc-cur.

The UFES (ultra-fast earthing switch) is a com-bination of devices consisting of an electronic device and the corresponding primary switch-ing elements which initiate a three-phase grounded bolted fault in the event of a fault. The extremely short switching time of the pri-mary switching element, less than 1.5 ms, in conjunction with the rapid and reliable detec-tion of the fault, ensures that an arc fault is ex-tinguished almost immediately after it arises. With a total extinguishing time of less than 4 ms after detection, an active protection concept with the UFES enables switchgear installations to achieve a highest possible level of protection for people and equipment.

—Advantages:

- Increased system and process availability to maintain com-petitiveness - Increased switchgear opera-tor safety during or after maintenance work - Reduced repair costs by mini-mizing the effects of faults on the system

- Minimization of pressure relief measures by application of ac-tive protection concepts - Reduction of incident energy be-low (1) cal/cm2. As per OSHA regulations, this brings the haz-ard risk category to zero.

Avoidance of the severe effects of an arc fault, such as:• Extreme pressure• Temperature rise up to 20,000 °C• Burning/vaporization of metal and insulating ma-

terial• Release of particles and hot gases• Intensive light/high acoustic stress

—UFESTM

Arc fault protection device for switchgear

The occurance of an arc fault, the most serious fault within a switchgear system, is associated with extremely high thermal and mechanical stresses in the area concerned.

—UFESTM

Ultra-fast earthing switch

—UFES primary switching element type U1

Electrical maximum characteristics for each voltage category (different types available)

Rated voltage (ms)* kV 1.4 17..5 27 36

Rated power frequency withstand voltage (rms) kV 5 42 60 70

Rated lightning impulse withstand voltage (peak) kV 12 95 150 170

Rated frequency Hz 50/60 50/60 50/60 50/60

Rated short-time withstand current kA 100 50 63 40 40

Rated peak withstand current kA 220 130 165 104 104

Rated duration of short-circuit s 0.5 3 2 3 3

Rated short-curcuit making current kA 220 130 165 104 104

Mechanical properties

Dimension (diameter x height) mm (in) ~137 x 210 (~5.4" x 8.3")

Closing time ms < 1.5

Contact bounce time ms 0

Service life expectation

Number of closing operations 1

Mechanical years up to 30

Micro gas generator years up to 15

—01 Arc extinction within ≤ 4 ms (after detection)

—01 The Ultra-Fast Earthing Switch elimi-nates the arc fault well before the first peak of the fault current—02 Example pressure curves, with and without UFES, in a compartment of an air-insulated me-dium voltage switchgear system with an internal arc fault current of 130 kA (peak) / 50 kA (rms)—03 Primary switching element for one phase

Epoxy resin insulation

Fixed contact

Ceramic insulator

Movingcontact pin

Rupture joint

Piston

Cylinder

Movingcontact system

Micro gasgenerator

—01

—02

—03

* 40.5 kV on request

D E SCR IP TI V E B U L L E TIN 76 U F E S T M U LTR A - FA S T E A RTH I N G S W ITCH

UFES electronics type QRU100 - Standard electronic tripping unit for the combina-

tion with ABB arc protection system REA - Two Optolink inputs for connection of the REA101

relay - Two high-speed inputs (HSI) - Self-monitoring - Optolink supervision - Testing mode for functional check - DIP switch configuration - Ideal for extension of existing ABB arc protection

systems - Alternative: Fault detection by non-ABB system

(compatibility verification required)

UFES primary switching element type U1 - Ultra-fast operating mechanism with micro-gas

generator - Vacuum interrupter - Compact design - Versatile in installation - Long service life

ABB arc protection system REA - Optical detection via line or lens sensors - Overcurrent detection - Selective protection - Circuit breaker failure protection

—UFES Active protection for switchgear

—01 UFES electron-ics type QRU100—02 UFES primary switch-ing element type U1—03 REA system

—01

—02

—03

Industries are facing internal and external dead-lines to perform arc flash mitigation within their facilities. The UFES is a unique solution to miti-gate arc flash risks. Tests based on IEEE Stan-dard 1584 (arc flash calculation standard) of the combination of a fuse based switch and an ul-tra-fast earthing switch applied between the fuse’s load side and the transformer’s primary connection have documented that.

During the test, an arc was initiated in the low voltage switchgear that was connected to the transformer. The UFES was able to successfully extinguish the arc within 4 ms by three-phase grounding on the MV system that was subse-quently cleared by the fuses so quickly that the system barely felt any disturbance. No arcing, just rapid fault clearing. Moreover, the LV switchgear sustained no visible damage and re-

—01 UFES applica-tion (example)—02 Circuit breaker compartment after 60 kA arc fault with UFES protection

mained in working condition. With this test, ABB also proved that this arc flash solution on medium/low voltage systems using UFES is able to reduce the incident energy below (1) cal/ cm2. As per OSHA regulations, this brings the hazard risk cate-gory to zero.

—UFESApplication example

CT

Optolink(trip)

Medium voltage bus

X

UFES PSE

UFESQRU 100

REA101

X Switch

Light sensor

XXX

xfmr

Low voltage bus

x

—01

—02